1. Field of the Invention
This invention relates broadly to surgical devices. In particular, this invention relates to a surgical clip applier which is adapted for use through an endoscope and may be used to clamp and/or suture, ducts, vessels, and other tissues, to anchor a tissue, or to attach a foreign body to a tissue. In addition, this invention relates to a flexible surgical device adapted to provide a relatively large pushing force at the distal end of the device relative to an outer tubular element of the device. For purposes of the invention, xe2x80x9cpushing forcexe2x80x9d is defined as a force transmitted from a proximal handle to a distal end of a flexible advancing element extending through the outer tubular element which imparts compression to the advancing element and tension to the outer tubular element.
2. State of the Art
Surgical clips are generally used to apply clamping force to ducts, vessels, and other tissues. In addition, surgical clips are particularly useful in controlling bleeding of a tissue in lieu of suturing or stapling where suturing or stapling is difficult.
All of the currently available surgical multifiring clip appliers are substantially rigid devices intended to extend through a trocar port or through an incision to a surgical site requiring application of a clip. The devices have been rigid because a stiff pushing element has been required in order to exert the required pushing force to move the clip over the tissue.
However, there is a substantial need for a flexible clip applier, particularly one insertable through a lumen of an endoscope. The ability to apply clips through an endoscope would permit myriad minimally invasive surgical solutions to medical problems, especially those of the gastrointestinal tract. However, it is accepted theory that the transmitted force required to advance or form a clip over tissue cannot be produced in the distalmost end of a long flexible device that is commonly constructed with a metal tubular coil, or polymer tube, such as an endoscopic device or catheter. For example, C. Paul Swain, MD, a recognized expert in endoscopic instruments and particularly endoscopic stapling devices, has stated that xe2x80x9c[i]t is hard to exert more than 200 g of force on the tissue when pushing . . . . This fact is of course one feature that makes intervention at flexible endoscopy relatively safexe2x80x9d. See C. Paul Swain, xe2x80x9cWhat Endoscopic Accessories Do We Really Need?xe2x80x9d, Emerging Technologies in Gastrointestinal Endoscopy, Gastrointest. Endosc., Vol. 7, No. 2, pp. 313-330 (April 1997). Yet, a pushing force substantially greater than 200 g is required to push-a clip over compressed tissue. In fact, it is believed a force in excess of 500 grams (1.1 lbs) is required for a satisfactory instrument, and substantially greater forces, e.g., in excess of 1500 grams (3.3 lbs) would be desirable.
Generally a flexible endoscopic device (e.g., a biopsy forceps device) includes an outer tubular member, typically being constructed of a metal tubular coil or a polymer tube which is poor in transmitting forces that impart tensile stresses to the outer sheath, a control element longitudinally movable relative to the tubular member, an end effector coupled to the distal ends of both the tubular member and the control element such that relative movement of the control element and the tubular member causes operation of the end effector, and a handle which moves the control element relative to the handle. This type of flexible endoscopic instrument is limited in the amount of pushing force it can generate for several reasons. Compression of a flexible control element (pushing element) tends to cause the pushing element to buckle within the outer flexible sheath of the device. If a relatively larger diameter flexible pushing element is used such that it better resists buckling, the pushing element may impart too much stiffness to the flexing of the endoscopic instrument. In addition, a flexible pushing element of larger diameter is subject to greater frictional forces within the outer sheath which reduces the force transmitted from the handle to the end effector. If the flexible pushing element is made relatively smaller in diameter, it is subject to kinking which will result in little to no force transmitted to the distal end. Kinking is especially a problem in endoscopic instruments, as the endoscope and its lumen may be extended through a tortuous path. For these reasons and others, mechanical application of a relatively large distal end pushing force and particularly clip application have been absent from the capability of flexible endoscopic tools.
It is therefore an object of the invention to provide a flexible endoscopic device capable of generating a relatively large pushing force at its distal end.
It is another object of the invention to provide an endoscopic clip applier.
It is a further object of the invention to provide a flexible clip applier which can exert a pushing force of at least 500 grams (1.1 lbs), and preferably in excess of 1500 grams (3.3 lbs) via a manually actuatable handle.
It is an additional object of the invention to provide a surgical clip applier which is adapted for use in minimally invasive surgery.
It is also an object of the invention to provide a surgical clip applier which has a pushing element which is not subject to kinking.
It is yet another object of the invention to provide a surgical clip applier which has a pushing element which does not create unsuitably high frictional forces within the outer sheath.
It is still a further object of the invention to provide a surgical clip applier which can store and apply multiple clips.
In accord with these objects, which will be discussed in detail below, a surgical clip applier is provided having a flexible, preferably flat wire wound outer tubular coil, a pair of jaws at the distal end of the tubular coil, a set of end effector wires extending through the outer tubular coil and coupled to the jaws, and a clip-advancing wire extending through the tubular coil. A lubricious, preferably extruded polymer, multilumen barrier sheath extends within the tubular coil and separates the wires from each other and the tubular coil. A clip chamber is provided in the distal end of the tubular coil and stores a plurality of linearly arranged clips. A clip pusher is provided at a distal end of the clip-advancing wire, and adapted to advance the clips in the chamber toward the jaws when the clip-advancing wire is advanced through the barrier sheath and outer tubular coil. The jaws include clamping surfaces which operate to compress tissue between the jaws when the jaws are closed, guides in which a distalmost clip rides distally and is advanced over the clamped tissue when the line of clips is advanced by the clip pusher, and a distal anvil which operates to bend a portion of the distalmost clip to enhance its retention on the clamped tissue. A proximal handle is provided for movement of the clip-advancing wire and end effector wires relative to the barrier sheath to effect (1) clamping and rotation of the jaws (relative to each other and about the longitudinal axis of the tubular coil), and (2) advancement of the clip-advancing wire to effect distal movement of a clip.
The flat wire wound tubular coil is preferred over round wire (though not necessarily required over a round wire wound tubular coil) because it is flexible, yet sufficiently longitudinally stiff such that the device may be pushed through the lumen of the endoscope. In addition, the flat wire wound tubular coil can be made with a high preload and has a tensile spring constant sufficiently high that it resists buckling and uncoiling during application of a pushing force by the handle against the clip-advancing wire. The clip-advancing wire has a sufficiently large diameter to transmit force, yet small enough to minimize internal friction when moved within a device flexed through a tortuous path in an endoscope. The end effector wires are large enough to handle the high closing force from the handle, and to resist compressive buckling when moved in an opposite direction, yet small enough to be coupled to diminutive jaws. The multilumen barrier sheath supports the clip-advancing wire and end effector wires along their length to reduce compressive buckling, and provides a separation layer to reduce friction. Movement of the clip-advancing wire relative to the outer tubular coil causes a compressive force in the clip-advancing wire and tensile forces in the outer tubular member such that a relative pushing force is transmitted to the distal end of the clip-advancing wire in excess of the perceived threshold of the 200 grams (0.44 lbs). In fact, one embodiment of the device of the invention, sized for endoscopic use, provides a pushing force in excess of 2267 grams (5 lbs).
In operation, the jaws can be moved through a working channel of an endoscope in a closed position. Once exited, the handle can be operated to open the jaws and rotate the jaws to a desired orientation. The jaws are positioned on either side of tissue about which it is desired to place a clip and the handle is operated to pull the end effector wires such that the jaws clamp about the tissue. The handle is then locked to maintain the jaws in the clamped position. The handle is operated to effect advancement of the clip-advancing wire through the tubular coil such that a clip is advanced through the jaw guides and over the tissue. The clip is advanced until a portion thereof is forced against the anvil of the jaws to effect bending of the clip portion such that that portion moves laterally to pierce the clamped tissue. After the clip is applied, the jaws are released from about the tissue, and the end effector assembly may then be moved to another tissue location to apply additional clips.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.